1. Field of the Invention
The present invention relates to a prefabricated-type concrete basement suitable as a part of a dwelling, and more particularly, to basements constructed of underground units made of a plurality of precast concrete blocks bound to one another to form a unitary rectangular enclosure. This invention also relates to a process for constructing such basements, and to dwellings with such basements.
2. Prior Art
Due to housing shortages in recent years, and for various other reasons, it has become highly desirable to provide basements or below-ground living spaces in ordinary dwellings.
Heretofore, the basements of houses have often been constructed primarily as underground storage spaces or storehouses, and accordingly, the basements were constructed as enclosures which were fitted in excavations and set in the ground by anchor bolts, and the unoccupied part of the excavations thereafter being filled (cf., e.g., Japanese Patent Application No. Hei-1-15663).
However, the basements of the aforementioned construction, which are constructed so as to be suitable as underground warehouses, enclosed relatively small interior spaces and therefore failed to provide sufficient space for living. Therefore, these types of basements have recently been made of reinforced concrete and in much larger sizes.
Reinforced concrete basements as described above are generally constructed, for example, by in-situ concrete deposition which is carried out by first performing excavation of the ground in an area broader than the size of the basement to be constructed. The excavation is performed to a predetermined depth by means of a power-shovel or the like to form a hollow area; gravel or the like is placed on the bottom of the hollow area, and then concrete is poured on the gravel bed to produce a concrete foundation. Then, reinforcing steel or other reinforcing material for the floor is arranged in a latticework, and concrete is deposited around the floor reinforcement. At this time, in order to allow connection of the floor reinforcements with the reinforcements for the side walls, the floor reinforcement is provided so that upright bars are arranged so as to protrude from the surface of the concrete at positions where side walls are to be vertically provided. After the concrete floor portion sets, the upright bars protruding at the predetermined positions of the floor are connected to vertical bars of the side walls, and then horizontal bars of the side walls are connected to the vertical bars to construct the reinforcements of the side walls. After this, forms are assembled on both sides of the thus-constructed reinforcements of the side walls, and concrete is deposited in the cavities defined by the forms to produce the side walls. After the hardening of the concrete in the side walls, the forms are disassembled, and space remaining between the outside of the side walls and the side of the excavation is filled, thereby completing the construction of the basement.
However, in the conventional techniques for the construction of basements, construction is performed by pouring concrete on-site, and as a result there arises various problems, for example, poor operational efficiency and prolonged construction period. In addition, construction operation involving concreting on-site has the problem that when constructing side walls, space for assembling frameworks must be provided on both sides of the side wall reinforcements, and this requires excavation over an area broader than the area the finished basements will occupy, resulting in increased cost.
Accordingly, the present inventors have conducted research to solve the above-described problems, and as a result they have found that when an entire basement is instead constructed by connecting precast concrete blocks, not only is the efficiency of operation on-site increased, but also the area of ground excavated may be decreased since the basement can be formed simply by setting or installing the blocks.
However, problems remain to be solved in that merely partitioning the inside of the basement into blocks when pouring concrete results in the size of the individual blocks to increase and thereby requires increased operation to connect blocks to one another.
When basements are made of precast concrete, particular care must be taken with respect to waterproofing, and a problem arises in that operations to ensure waterproofing decrease the efficiency of operation on-site.